B1911 code definition

The B1911 trouble code signals a circuit error from the airbag diagnostic monitor.

What the B1911 code means

The B1911 code is a standard OBD-II trouble code that detects an airbag diagnostic monitor circuit malfunction. The airbag diagnostic monitor, which is commonly referred to as the airbag control module, serves two primary functions. The first is to receive data from the airbag crash sensors when the vehicle is in an accident, and relay that information to the airbags, which will be deployed. The second function is to monitor the airbag system when the vehicle is started, to make sure that all of the components are operating and responding. If the body control module or powertrain control module (PCM) detect an abnormal reading from the airbag diagnostic monitor circuit, then the B1911 code may be stored.

What causes the B1911 code?

The most likely cause of the B1911 code is an electrical failure in the airbag deployment system, or in the diagnostic monitor. Blown fuses, corroded and loose connectors, and short circuits and wires all frequently cause the B1911 code to be stored. A defective airbag diagnostic monitor is another common cause. In some cases, the diagnostic monitor will need to be reprogrammed, though that is less common.

What are the symptoms of the B1911 code?

A vehicle with the B1911 trouble code will likely have an illuminated or flashing airbag Warning Light, as well as an illuminated check engine soon warning light. In most cases, the airbag system will be inoperable, so the airbags will fail to deploy in the event of an accident.

How does a mechanic diagnose the B1911 code?

The B1911 code will be diagnosed with an OBD-II trouble code scanner. A reputable mechanic can use the scanner to view the freeze frame data and gather information about the B1911 code, while also looking to see if there are any additional trouble codes present. If there are multiple codes, then the technician should diagnose them in the order that they are displayed in. The trouble codes will then be reset, the vehicle restarted, and the B1911 code checked for. If the code is no longer detected, then an intermittent error, or an inaccurate detection are the likely culprits.

If the B1911 code is still detected, then the mechanic should visually inspect all of the electrical parts in the system, and replace any and all damaged fuses, wires, or connectors. Next, the airbag diagnostic monitor should be carefully inspected. It is fairly common for the internal thermal fuse to be blown, but this fuse cannot be replaced. The fuse is blown not because of a resistance issue, but deliberately by the airbag diagnostic monitor when a short in the airbag deployment system is detected. This occurs to prevent spontaneous airbag deployment. Since the fuse cannot be replaced, the diagnostic monitor will need to be replaced, as will the electrical error that caused the issue.

After any part is replaced, the technician will again reset the trouble codes, restart the vehicle, and check to see if the code is still present. This will help the mechanic know when the problem is resolved.

Common mistakes when diagnosing the B1911 code

The most frequently made mistake when diagnosing the B1911 code is the failure to adhere to the OBD-II code diagnosis protocol. The protocol should by complied with at all times, as doing so increases the chances of an accurate and thorough diagnosis.

It is common for electrical components to be overlooked when diagnosing the B1911 code. This can result in replacing the airbag diagnostic monitor without addressing the electrical error that caused the internal thermal fuse to blow. When this occurs, the new airbag diagnostic monitor will also be damaged and fail, resulting in a costly second replacement.

How serious is the B1911 code?

The B1911 trouble code will not keep a car from being drivable, or even present any drivability concerns. It will likely keep the airbag system from operating properly, however, which means that the airbags will likely fail to deploy if an accident occurs. Airbags are vital safety features that can limit damage and save the lives of the driver and passengers, so the car should not be driven until it has been diagnosed and repaired.

What repairs can fix the B1911 code?

Additional comments for consideration regarding the B1911 code

The B1911 code is a manufacturer specific trouble code. Manufacturer specific codes vary in definition depending on the automaker. While the B1911 code represents an airbag diagnostic monitor circuit malfunction in some vehicles, it may detect an entirely different error in other cars. It’s important for technicians to always take into account the vehicle they are inspecting when diagnosing this code.

Whenever the airbags are deployed, the airbag diagnostic monitor will need to be either replaced, or reprogrammed.

Need help with a B1911 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

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